Tech 1 Interceptors are the tech 1 aerial anti-air solution. They are pretty cheap to build, and more efficient in numbers. They have a longer firing range than their vision radius, so adding air scouts to their rank will increase their effectiveness. A good guideline is to mix one scout in with every five to ten interceptors.
Interceptors are sometimes used to replace scouts due to their superior survivability. They have a better chance of coming back alive from over an enemy base. Furthermore, once in sufficient numbers, they can cover enough ground to replace scouts and reduce micro-management.
Interceptors fare well against tech 1 anti-air solutions, thanks to their high mobility, and will only go down under sustained fire. They will get decimated by tech 2 flak fire, mobile or not, so avoid these at all costs!
Interceptor squadrons actually fare pretty well against SAM turrets, but this is only because of the SAM's low rate of fire, combined with complete overkill, which severely decreases the SAM's effective DPS.
Mass for Mass, a squadron of 10 tech 1 interceptors can take on an equally priced tech 3 air superiority fighter. It is, however, still advised to move up to tech 3 air superiority fighter and tech 2 fighter-bombers as soon as possible. Reasons include a faster build rate, and a lower unit cost. Also, air superiority fighters have a higher survival rate, and can return to base for refuel and repair. Air superiority fighters have a speed of 25, compared to the interceptor's speed of 15. Finally, air superiority fighters are fast enough to avoid flak, while multiple interceptors can sometimes be taken down in a single flak shot.
Because interceptors come with only 5 minutes of fuel, it is not recommended to have them blindly patrol around your base. Fuel-less interceptors are virtually sitting ducks to all other forms of anti-air, as not only do they fly at a fraction of their speed, they lose the use of their weapons. If you haven't yet reached tech 2 and therefore can't build an air staging facility, you can land your interceptors periodically somewhere out of harm's way so that they can regenerate their fuel. Once you do have a refueling base, you can get your interceptors patrolling again until you have enough fighter bombers to take the job over.
The four tech 1 interceptors are the UEF Cyclone, the Cybran Prowler, the Aeon Conservator and the Serapim Ia-atha. These units are mostly equal stat wise, except for minor HP differences, and weapon differences (ROF, mostly, but equivalent effective DPS). While in the original supreme commander, the aircraft's low amount of HP made those weapon differences stand out (The Cyclone could destroy any interceptor in one shot, but fired very slow), this is not the case in Forged Alliance. The differences are imperceptible in game, and only extreme sandbox games with heavy cookie-cutting analysis can show a difference in result. In other words: they are functionally identical.
However, in comparing DPS and health, la-atha is the best, with the cyclone a close second, conservator in third, and the prowler in fourth, however, a few players claim the prowler and the la-atha are the hardest to hit, due to their thin profile.